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Qls-1

M

mbeigh

Active Member
I might pick up a pair of QLS-1 speakers. I was thinking of vertically bi-amping them using a Mac 2002 on top and an Adcom gfa-555 on the woofer.
I would be using an anthem pre-1 tube preamp to control them. Would this work? Both the amps are 200w but I think the adcom is more high current and stable at lower draws. I have no experience with biamping, but have all the equipment but the speaks. would this be worth my time and effort?

Thanks, M Beigh
 
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I love mine, after a bit of work on them, thanks to cdfac's great thread...
http://www.audiokarma.org/forums/showthread.php?t=166374
Check it out. If the pair you're looking at are in good shape and you have the room for them (and a strong back to move them) they are very fine speakers. You should be fine with your amps to start with, though the Watkins woofers will want even more power than 200 watts. Remember these are only 81db at 1 watt/1 meter.

I haven't experienced either amp you mentioned so others can comment on them, is that 200 wpc at 8 ohms? How about at 4 ohms?

BTW, as I understand it what you're describing is horizontal biamping, vertical would be one amp per speaker, horizontal is one amp for bass, the other for mids & highs. I believe I've read that it's best to have identical amps for vertical biamping, but it can help with the load on single tranny amps to vertically biamp.

My present setup is horizontally biamped, 590wpc at 4 ohms for the Watkins, 340wpc for the mids & emits and gets as loud as I'll ever need before clipping in my space.
Hope that helps,

Jim
 
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Jim,

The Adcom GFA-555 II is rated at 325 W continuous average power 20 to 20,000 Hz into 4 Ohm.

The manual states that any speaker system having a nominal impedance down to 2 Ohm can be connected. It recommends that a dedicated circuit be used for the amp and the maximum power consumption is 1500 VA.

Edit - oops, OP didn't state mark II but specs are the same for output. Power consumption was not listed in the GFA-555 manual, but should be the same I would think.
 
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My other possible option is to use the tube amplifier in my Jolida 502B for the top end and the Adcom for the woofers. I am also considering looking for a pair of Kappa 9s. What do you think about either of those combos?
 
mbeigh said:
My other possible option is to use the tube amplifier in my Jolida 502B for the top end and the Adcom for the woofers. I am also considering looking for a pair of Kappa 9s. What do you think about either of those combos?
Click to expand...

Do your homework thoroughly on using the tube amp. The crossover is at 200 Hz (Watkins to mid-bass), so there is still a significant power requirement for the mid-hi section.

Check out http://sound.westhost.com/bi-amp.htm#bi_wiring, there is a table showing the power split at different frequencies. According to this there is still about 60% - 70% going to the upper section of drivers.

Hopefully someone using tubes here on the same speakers can comment. Without knowing the impedences/power draw on the QLS upper driver section, I'ld be hesitant to go with tubes.....would be nice though wouldn't it? :music:
 
mbeigh said:
My other possible option is to use the tube amplifier in my Jolida 502B for the top end and the Adcom for the woofers. I am also considering looking for a pair of Kappa 9s. What do you think about either of those combos?
Click to expand...

What Ken said. Ask cdfac about Kappa 9's vs QSL's as he's had both. For me it's no contest, but I only heard 9's for a short time in another system years ago.
 
McIntosh MC 2002

ELECTRICAL: 200w/ch into 8 ohms, 300w/ch into 4 ohms. (600w mono into 8 ohms). Response 20-20kHz (+0 -0.25dB). Distortion 0.01%. Noise and hum -100dB. Output direct coupled for 4 to 8 ohms. No autoformers. Damping factor 100 or greater. Input impedance 20k. Input sensitivity 1.4v or 2.5v. Sentry Monitor. Power Guard.

FRONT PANEL: Glass panel. Illuminated. Power level meters (linear watts or dB). Power Guard lamps: normal or limit. Temp lamp. Illuminated power sw: on or off.

BACK PANEL: Output barrier strip. Audio inputs. AC outlet. Input level sw: 2.5v or 1.4v. Mode sw: stereo or mono. Fuse. Panloc mounting.

Size 7-1/8"H, 16-3/16"W and 14-1/2"D. Weight 50 lb. Sold from 1984-1988. Last retail price $1850.00

From http://www.roger-russell.com/amplif1.htm#mc2002

Nice pic here - http://www.audioclassics.com/detail.php3?detail=MC2002&nav=cat

Looks like a pretty stout performer for the top end though ???????????
 
the K9's will have better clarity in some regions, but it was the relative seamlessness of the QLS1 that i loved, and the tight tuneful bass that never quits (if the amp is up to it). i was looking at those same QLS1's, mbeigh. they will be well worth the price. some day i will probably have another pair, i liked them that much.
 
mbeigh said:
I might pick up a pair of QLS-1 speakers. I was thinking of vertically bi-amping them using a Mac 2002 on top and an Adcom gfa-555 on the woofer.
I would be using an anthem pre-1 tube preamp to control them. Would this work? Both the amps are 200w but I think the adcom is more high current and stable at lower draws. I have no experience with biamping, but have all the equipment but the speaks. would this be worth my time and effort?

Thanks, M Beigh
Click to expand...

What you describe using one amp on the woofers and the other for the mids and highs is a horizontal bi amp...NOT vertical
 
I have biamped my QLS-1's most of their life. I used an active crossover splitting the frequency prior to amplification. This minimized the demand on the amps. For a long time I ran a Nikko Alpha 450 (220w/ch) on the top and another on the bottom. The demand on these amps were almost identical (depending on the music). The speaker loads seemed very balance from hi freq to low freq demands. I run 2 Nikko Alpha 650's (330 w/ch) and while the audible difference is minimal there is a little more headroom just for comfort.
 
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